Apparatus and method for transforming an input sound signal

ABSTRACT

An apparatus for transforming an input sound signal comprises a synthesiser which manipulates, in accordance with a manipulation parameter, a pitch deviation envelope to derive a manipulated pitch deviation envelope. A filter transforms the input sound signal from a resampling of the input sound signal with respect to the manipulated pitch deviation envelope. The manipulation parameter may be a user-defined peak pitch deviation of an output sound signal. Another apparatus for transforming an input sound signal comprises a synthesiser which manipulates, in accordance with a manipulation parameter, a pitch deviation envelope selected with reference to the manipulation parameter to derive a manipulated pitch deviation envelope.

The invention relates to an apparatus and method for transforming aninput sound signal. At least one of the disclosed techniques can be usedfor synthesising a scratched sound, such as a disc jockey (DJ) couldproduce.

In a basic DJ's setup, two turntables connect to a DJ mixer whichpre-amplifies the turntable outputs and mixes them according to theposition of a slide controller on the turntable crossfader. During atypical scratch, the DJ controls one turntable with one hand to changeits playback rate and the crossfader with his other hand to fade in andout this turntable output. The remaining turntable usually plays somebacking music.

Scratching is considered by many as the primary technique for playingthe turntable as a musical instrument making “new” sounds from recordedsounds on vinyl records by altering the way they are played. The term“turntablism” is loosely defined as the act of performing on theturntable. Some consider turntablism to be a musical genre in its ownright. Turntablists—that is, DJs who practice turntablism—change therate of playing records with hand movements to produce scratched sounds.Many DJs play as expressively as any traditional instrumentalist, withcontrol of the duration, loudness, articulation, and timbre ofindividual scratched sounds.

Turntablists produce different types of scratched sound with differentscratching techniques; that is, the techniques implemented when the DJmoves the record on the turntable and/or the crossfader slide. Thetechniques for three fundamental types of scratches [1] are as follows:

-   -   Stab: while moving the record in the forward (i.e. “normal)        direction of play, the DJ fades the sound in and out;    -   Reverse: the same as stab except that the record is moved in the        reverse direction;    -   Chirp: the DJ moves the record forward, fading the sound out;        then the DJ moves the record in reverse, fading the sound in.

Recently DJing software has allowed DJs to extend their scratchingtechniques to manipulation of digital sound files. Broadly speaking,current DJing systems are able to generate time-varying rates of playback of sound files based on gestural data, graphical representations orstored patterns. Gestural—e.g. hand movement—data is captured bycontrollers such as control records (on ordinary turntables) [7],computer mice [4, 6], and optical sensors and accelerometers [3].Graphical representations involve plotting changes in the playback rateover time [5].

Other systems store patterns of these changes for common scratchingtechniques [4, 6], and among them Skipproof allows limited modificationsto the patterns [4]. However, it is possibly true to say that not even aproficient turntablist knows the exact changes in the playback rates fordifferent scratches. This makes graphical representations of scratchesnot intuitive. Further, it makes synthesis/reproduction of scratchesparticularly difficult, especially for the unskilled DJ—i.e. DJs withminimal or no DJing/turntablist skills.

Further, there is no standard scratching notation. Though not in wideuse, the Turntablist Transcription Methodology is a comprehensive gridsystem where changes in the playback position in the record are written[2]. An illustration of such notation is given in FIG. 1. With playbackposition on the Y-axis and time on the X-axis, a straight line with agradient of two can be used to represent a scratch with twice the normalplayback rate. Notational curves represent time-varying playback ratesfor scratches. This notation is aimed at communicating general musicalideas to human turntablists, but is not sufficiently precise forsynthesis purpose.

Although gestural data preserves expressiveness, it is hard formusicians without DJing skills to execute the correct movements.Pattern-based systems such as those described above, do not require anyDJing skills but in their current form these systems provide no means ofallowing a DJ to create expressive turntablism performances.

Known techniques such as additive analysis/resynthesis are disclosed in,for example, [9]. Such known techniques as those typified by [9] uselinear analysis which is particularly unsuitable for scratchingtechniques.

The invention is defined in the independent claims. Some optionalfeatures of the invention are defined in the dependent claims.

An apparatus incorporating the features of the independent claims mayallow synthesis of scratched sounds by musicians, thereby enabling themusicians to describe scratches, scratch strokes and their acousticcharacteristics in a musical, concise and reproducible notation. Such anapparatus is capable of producing a minimum of three types of scratches.With this repertoire, it is possible for musicians to create realisticand expressive performances. Further, the disclosed techniques allowusers without a DJing skillbase to create realistic scratched soundsfrom and for music production, allowing creation of new sounds beyondsimple stored patterns. In one implementation, the techniques may beused in a personalisable ringtone generator for mobile telephoneringtones.

The present invention will now be described, by way of example only, andwith reference to the accompanying drawings in which:

FIG. 1 is a notation chart illustrating the Turntablist TranscriptionMethodology;

FIG. 2 is a block diagram illustrating an architecture of an apparatusfor transforming an input sound signal;

FIG. 3 is a process flow diagram illustrating a technique fortransforming an input sound signal;

FIG. 4 illustrates stroke tables of pitch deviation envelopes;

FIG. 5 illustrates a manipulated stroke table for a stab-forward stroke;

FIG. 6 is a block diagram illustrating the resampling process utilisedin the playback of a manipulated stroke table; and

FIG. 7 is a process flow diagram illustrating a technique for derivingand storing pitch deviation envelopes suitable for use in thesynthesising of a scratched sound.

An apparatus for transforming an input sound signal (usable to providean output or “scratched” sound) is illustrated in FIG. 2. The apparatus10 comprises principally a synthesiser 12 configured to manipulate, inaccordance with a manipulation parameter, a pitch deviation envelope toderive a manipulated pitch deviation envelope; and a filter 18configured to resample the input sound signal from a resampling of theinput sound signal with respect to the manipulated pitch deviationenvelope. These techniques will be discussed in more detail below.Optionally, the apparatus also comprises the following components:

-   -   receiver module 14 configured to receive a user's choice of the        manipulation parameter. This may be a user-defined peak pitch        deviation of the output sound signal and/or defined in terms of        duration and scratch type of the desired output sound;    -   selection module 16 configured to select the pitch deviation        envelope from a plurality of pitch deviation envelopes.        Therefore, manipulation of the pitch deviation envelope is a        manipulation of the selected pitch deviation envelope selected        by selection module 16. The selection module 16 selects the        pitch deviation envelope with respect to the manipulation        parameter;    -   memory 20 for, amongst other things, storing a pitch deviation        envelope as a stroke table and a template input sound signal.        The library of stroke tables is stored in memory 20;    -   a graphical user interface (GUI) 22 to allow a user to control        the apparatus 10;    -   recording module 24 including, for example, a microphone and        suitable processing circuitry (neither of which are illustrated)        to allow a user to record one or both of an input sound signal        to be transformed and a template sound signal for use in        creating one or more pitch deviation envelopes in a library        stored in memory 20; and    -   speaker module 26 and suitable processing circuitry (not shown)        for outputting an audible sound signal which is a transformed        version of the input sound signal.

In one implementation the apparatus 10 is a computer apparatus whichimplements the disclosed techniques either in hardware, software or in acombination thereof. The apparatus may be configured to read, from acomputer readable medium, executable code for implementing the disclosedtechniques. In another example, the apparatus 10 is a mobile telephoneapparatus where memory 20, GUI 22 (mobile telephone display and keypad),recorder module 24 (mobile telephone microphone and processingcircuitry) and speaker 26 (mobile telephone earpiece and/or speaker andprocessing circuitry) are readily available standard mobile telephonefeatures.

For the purposes of the following description, some definitions are nowmade:

-   -   a scratched sound comprises one or a sequence of stroke sounds;    -   a stroke corresponds to a hand movement in either a forward or        backward direction;    -   a stroke sound is determined by at least a pitch deviation        envelope and, optionally, an amplitude envelope;    -   a pitch deviation envelope is a signal envelope defining the        pitch deviation of a stroke sound with respect to time;    -   an amplitude envelope is an envelope defining the signal        amplitude of the stroke sound with respect to time;    -   the pitch deviation envelope may be specified by one or more of        its peak pitch, its attack time (i.e. rise to the peak pitch)        and decay time (i.e. it's decay from the peak pitch);    -   a stroke table is a table for storing parameters defining the        pitch deviation envelope;    -   an output sound signal is a scratched sound which is a        transformed input sound signal manipulated according to a        user-defined parameter;    -   an input sound signal is a “scratchable unit”—that is, a sound        signal to which the described techniques can be applied to        produce a scratched sound;    -   a template input signal is a recorded sound which is used to        derive pitch deviation envelopes for use in the        scratching/transformation of the input signal.

A second apparatus (not shown) for transforming an input sound signalcomprises a synthesiser for manipulating, in accordance with amanipulation parameter, a pitch deviation envelope selected withreference to the manipulation parameter to derive a manipulated pitchdeviation envelope. The manipulation techniques of this apparatus may beas for synthesiser 12 of FIG. 2 described below. In this apparatus, thepitch deviation envelope may be selected by selection module 16 of FIG.2 as described below.

Referring now to FIG. 3, the process flow of a technique fortransforming an input sound signal is described. The process begins atstep 50. At step 52, an input sound signal (a scratchable unit) isrecorded by the user using recorder module 24. The input sound signal isstored in memory 20.

At step 54, synthesiser 12 makes reference to a user-selectedmanipulation parameter. This may be received from the user at receivermodule 14. The process is discussed in further detail below, but in oneimplementation, the manipulation parameter is a user-defined peak pitchdeviation of an output sound signal defined by the user through GUI 22.That is, the user defines the desired peak pitch deviation of the outputscratched sound.

At step 56, synthesiser 12 manipulates the pitch deviation envelope inaccordance with the user-defined manipulation parameter, e.g. thedesired peak pitch deviation of the output scratched sound.

At step 58, filter 18 resamples the input sound signal with respect tothe manipulated pitch deviation envelope.

At step 60, the transformed input signal—i.e. the scratched sound—isoutput as the desired output sound signal by the apparatus 10 fromspeaker 26.

In one implementation, the manipulation at step 56 takes the form of ashift of the pitch deviation envelope in accordance with the peak pitchdeviation of the (desired) output sound signal. That is the envelope ofthe pitch deviation envelope is shifted in accordance with theuser-defined peak pitch deviation of the desired output sound signal.The shift corresponds to a peak pitch difference between a peak pitch ofthe pitch deviation envelope and a peak pitch deviation of the desiredoutput sound signal. The pitch deviation envelope may comprise at leastone of an attack portion and a decay portion, and the synthesiser isconfigured to stretch or trim the at least one of the attack portion andthe decay portion when shifting the pitch deviation envelope. Signalprocessing algorithms for these operations are described in greaterdetail with respect to FIGS. 4 and 5.

Prior to its manipulation, the pitch deviation envelope is selected froma library of pitch deviation envelopes by synthesiser 12. The pluralityof pitch deviation envelopes are defined by a respective plurality ofstroke tables (discussed below) and synthesiser 12 makes the selectionfrom a comparison of the user-defined peak pitch deviation of the outputsound signal with respective peak pitch deviation values of the pitchdeviation envelopes in the library.

As noted above, a scratched sound comprises one or a sequence of strokesounds, each of which is determined by at least a pitch deviationenvelope and, optionally, an amplitude envelope. Specifying the acousticdetails of a number of strokes tends not to be intuitive and can also betedious. A better representation would allow DJs and computer musiciansalike to describe strokes (and scratches) on a musical level. It wouldalso be concise and express main acoustic characteristics of thestrokes.

From a technical perspective, scratching is the result of playing back arecording at a time-varying rate. The rate of playback is expressed aspitch deviation ρ. The higher the pitch deviation, the faster therecording plays. ρ=1 when the playback rate is normal, ρ=2 when it istwice the normal speed, and so on. If the recording is digital, theperiod (in number/amount of samples) between a time it is sampled andthe time it is next sampled is equal to the value of ρ. Resampling ofthe digital signal allows for it to be reproduced at different playbackrates. The value of ρ is equal to the original sampling rate divided bythe new rate. The resampling process is described in greater detailbelow with respect to FIG. 7.

Taking into account a DJ's mental model of scratches and possible pitchdeviation and amplitude envelopes for human performances, a stroke maybe synthesised from the following parameters:

Parameter Name Data type Scratchable unit (time In Array of 16-bitsigned samples) integer Scratch name (e.g., “stab” scratchName Characterstring “chirp”, “reverse” and “letgo”) Direction (“fwd” or “back”) DirCharacter string Duration in seconds Dur Floating point number Peakpitch deviation in pitchDevPeak Floating point number semitones ([−24,24]) Attack time of pitch deviation attackP Floating point numberenvelope in seconds Attack time of amplitude attackA Floating pointnumber envelope in seconds Decay time of amplitude decayA Floating pointnumber envelope in seconds Initial playback position playPos Floatingpoint number

Receiver module 14 is configured to receive any one or more of the aboveparameters as the user-defined manipulation parameter for manipulationof the input sound signal by synthesiser 12.

A stroke corresponds to a hand movement in either a forward or backwarddirection. There can be silence between strokes, but each of the strokesis usually continuous. Playback of a scratched sound starts at itsbeginning, where the previous stroke ends, or at an arbitrary position.The peak pitch deviation of the stroke is related to the speed of thehand: the faster the hand, the higher the pitch. The attack and decaytimes of the stroke define the shapes of the pitch deviation andamplitude envelopes. For example, a simple stab scratch with one forwardstroke is specified by a user as follows:

; scratchName in scratch Stab “uh” 0 1 10000 ; Dir dur pitchDevPeakattackP attackA decayA playPos stroke Fwd .052 14.5 .023 .01 .01 0 0(The Lines Beginning with Semicolons are Comments.)

The first line of code is a scratch statement, and it begins thedescription of the stab scratch. The last line is a stroke statement,which specifies the acoustic parameters of an individual stroke. If ascratch includes several strokes, the DJ user may insert multiple strokestatements under the same scratch statement.

Turning to FIG. 4, a first pair of pitch deviation envelopes 100defining respective strokes are illustrated. The pitch deviationenvelopes 100 are defined and stored as respective stroke tables. Thefull variation of timbre of the strokes is defined over the range from−24 to 24 semitones. The two illustrated pitch deviation envelopes arefor scratch type stabs with respective peak pitch deviations ofapproximately −4 semitones and 13 semitones respectively. Dashed lines102 divide the pitch deviation envelopes 100 into two sections: theattack portion 106 before the peak pitch deviation 104 and the decayportion 108 after the peak pitch deviation 104. Generally speaking,pitch deviation increases from a start point 110 through the attackportion 106 to the peak 104 and then decreases over decay portion 108 toend point 112. However, sometimes—and depending on the nature of thestroke—the pitch deviation envelope 100 does not comprise an attackportion 106, or a decay portion 108.

The upper pitch deviation envelope 100 of FIG. 4 is a pitch deviationenvelope with a low pitch deviation corresponding to a slow stroke (thatis, a slow hand movement). The pitch deviation changes rapidly in thebeginning and at the end; that is, the gradient of the envelope atportions 106 and 108 is steep, increasing steeply at portion 106, anddecreasing steeply at portion 108. Otherwise the gradient is sustainedat about the peak deviation 104. On the other hand, the changes in pitchdeviation during the fast stroke of the lower pitch deviation envelopeof FIG. 4 (a stroke table with high pitch deviation) are gradual andcontinuous. The pitch deviation gradually increases over the relativelylong attack of portion 106, and starts decreasing from point 104 topoint 112 over portion 108.

It is these pitch deviation envelopes—stored as stroke tables—which areselected and manipulated with reference to the manipulation parameterdiscussed above to provide the manipulated pitch deviation envelope foruse in resampling the input sound signal. The pitch deviation envelope100 is manipulated/shifted according to the user's definition of thedesired peak pitch deviation of the output sound signal.

That is, synthesiser 12 modifies the parameters of the stroke table forthe specified scratch type and direction. Synthesiser 12 shifts theentire pitch deviation envelope 100 by the difference between the peakof the selected pitch deviation envelope and the peak of the specifiedoutput signal. The attack and decay sections 106, 108 of the envelopes100 are trimmed/shortened if they are too long or stretched if tooshort.

FIG. 5 illustrates a modified stroke table 120 for the stab scratchspecified in the stroke table above. It is derived from the matchedstroke table for a fast stroke, which has a peak pitch deviation 122closest to the user-specified (in the stroke table) peak pitch deviationof 14.5. The pitch deviation envelope 120 is multiplied by a constantfrequency ratio (equivalent to about 1.5 semitones). An initial portionof its attack has been trimmed off; that is, as the peak pitch has beenshifted “left” on the time X-axis, the initial portion of the matchedpitch deviation envelope was trimmed off, leaving a new start point 124of the envelope 120. It is also possible to shorten the attack portionby squeezing/compressing it rather than trimming, but trimming gives aperformance more in accordance with human perception. The entire decayportion 126 has been stretched to ensure the overall time of the pitchdeviation envelope remains constant or at least substantially constant.Alternatively, it is possible to extrapolate the decay portion 126 but,again, it is found that stretching provides better performance. FIG. 5thus illustrates a manipulated pitch deviation envelope for use inresampling of the input sound signal.

Referring now to FIG. 6, an off-line process of a technique for derivingone or more pitch deviation envelopes suitable for use in the synthesisof a scratched sound and storing these in a library in memory 20 is nowdiscussed. The process begins at step 150. At step 152, a template inputsignal is recorded by the user with recorder module 24 of apparatus 10.The sound may be any sound or speech signal as chosen by the user. Forexample, one might consider recording the sound of a user saying“aaaahhhh”. At step 154, plural versions of the template input signalare recorded, each recorded with different speeds of playback of thetemplate input signal. In one implementation of this, the sound“aaaahhhh” is recorded onto vinyl (i.e. a vinyl record), and the soundis scratched by a DJ using a turntable at various speeds/pitch deviationenvelopes. These various recordings are recorded by module 24. Fromthese recordings, the plural pitch deviation envelopes are derived forstoring in memory 20.

Like acoustic musical instrument tones, scratched sounds in the same“register” have a similar timbre. It is possible to synthesise strokesof close peak pitch deviations and the same scratch type and directionusing a stroke table. Several strokes may be recorded at different peakpitch deviations (usually 2-3 per octave) to allow variation in thetimbre over the full range from −24 to 24 semitones.

One technique for deriving the plural pre-determined pitch deviationenvelopes at step 156 comprises conducting a spectral analysis of thetemplate input signal and one or more of the plural recordings of thetemplate input signal (of time-varying speeds of playback). An alignmentof the respective spectra is carried out and from this the pitchdeviation envelopes are derived. The pitch deviation envelopes arestored in a library of stroke tables in, e.g., memory 20 at step 158.The process of FIG. 6 ends at step 160. The analysis/resynthesis processfor the playback at step 60 of FIG. 3 of the synthesised sound signal isillustrated with respect to FIG. 7. The original scratchable unit 200 ofFIG. 7 is an input sound signal as discussed above with respect to FIG.3.

FIG. 7 illustrates an overview of the resampling filter used forplayback at a time-varying rate. The input sound signal (labelled“scratchable unit,” 200) is resampled according to a pitch deviationenvelope 202 by bandlimited interpolation [8] through a low-pass filter204. Optionally, the scratched sound is scaled by multiplier 208according to the amplitude envelope. In one implementation, simple ASD(attack, sustain, decay) envelopes are used approximations to theamplitude envelopes, and there is no need to store any parameters forthe amplitude envelope(s). in such cases, the stroke tables define pitchdeviation parameters only.

The low-pass filter has a cutoff frequency dependent on the pitchdeviation, and a kaiser-windowed sinc kernel with stopband attenuationof −80 dB. The output 206 of filter 204 is multiplied by multiplier 208with an amplitude envelope 210, which is as long as the pitch deviationenvelope. The scratched sound is then output (step 60 of FIG. 3) fromspeaker 26.

When a new sampling point falls between the original points, the newsample value can be obtained by the bandlimited interpolation technique.Based on Shannon's sampling theorem, bandlimited interpolationreconstructs missing sample values by convolving the original sampleswith the sinc function. The sinc function serves as the impulse responseof a low-pass filter whose cutoff frequency is half of the lowest of theoriginal and the new sampling rates.

In summary, the described scratched sound synthesiser allows synthesisof a sound clip for playback at different time-varying rates specifiedby a user to imitate the sounds a DJ produces on a turntable withdifferent scratching techniques. The sound clip, called a scratchableunit, is usually speech with a single syllable. The scratched soundsynthesiser turns the scratchable unit into a scratch with one or morestrokes (e.g., a chirp scratch with a forward and a back strokes).

The invention has been described by way of example only and it will beappreciated that various modifications in detail may be made to thedescribed embodiments above without departing from the spirit and scopeof the claims. Features presented in one aspect of the invention may becombined with another aspect of the invention.

REFERENCES

-   [1] F. Broughton and B. Brewster, How to DJ right: the art and    science of playing records. New York, N.Y.: Grove Press, 2003, pp.    184-195.-   [2] J. Carluccio, E. Imboden, and R. Pirtle. (2006, Feb.)    Turntablist transcription methodology. [Online]. Available:    http://www.ttmethod.com/-   [3] M. C. Hans and M. T. Smith, “Interacting with audio streams for    entertainment and communication,” in Proc. 2003 ACM Multimedia,    Berkeley, Calif., 2003, pp. 539-545.-   [4] K. F. Hansen and R. Bresin, “DJ scratching performance    techniques: analysis and synthesis,” in Proc. 2003 Stockholm Music    Acoust. Conf., Sweden, 2003, pp. 693-696.-   [5] Image Line Software. (2007, May) FL Studio Wave Traveller.    [Online]. Available:    http://www.flstudio.com/help/html/plugins/Wave%20Traveller.htm-   [6] Ots Labs Pty Ltd. (2007, May) Ots CD Scratch 1200. [Online].    Available: http://cdscratch.com/-   [7] Rane Corp. (2007, May) Serato Scratch LIVE. [Online]. Available:    http://www.rane.com/scratch.html-   [8] J. O. Smith. (2006, Nov. 11) Digital audio resampling home page.    resample.pdf. [Online]. Available:    http://ccrma.stanford.edu/jos/resample/-   [9] Roads et al., The Computer Music Tutorial (MIT press, Cambridge,    Mass., 1995), pp. 144-156.)

1.-25. (canceled)
 26. Apparatus for transforming an input sound signal,the apparatus comprising: a synthesiser configured to select, withrespect to at least one manipulation parameter, a pitch deviationenvelope from a plurality of predetermined pitch deviation envelopes,and manipulate, in accordance with said at least one manipulationparameter, said pitch deviation envelope to derive a manipulated pitchdeviation envelope, the at least one manipulation parameter comprisingmusical and acoustic parameters; and a filter configured to transformthe input sound signal from a resampling of the input sound signal withrespect to the manipulated pitch deviation envelope.
 27. Apparatusaccording to claim 26, further comprising a receiver module configuredto receive the at least one manipulation parameter as a user-definedpeak pitch deviation of an output sound signal.
 28. Apparatus accordingto claim 27, wherein the selection module is configured to select thepitch deviation envelope from a comparison of the peak pitch deviationof the output sound signal with respective peak pitch deviation valuesof a plurality of predetermined pitch deviation envelopes.
 29. Apparatusaccording to claim 26, wherein the synthesiser is configured to derivethe manipulated pitch deviation envelope by shifting the pitch deviationenvelope in accordance with the peak pitch deviation of the output soundsignal.
 30. Apparatus according to claim 29, wherein the synthesiser isconfigured to shift the pitch deviation envelope by a peak pitchdifference between a peak pitch of the pitch deviation envelope and thepeak pitch deviation of the output sound signal.
 31. Apparatus accordingto claim 29, wherein the manipulated pitch deviation envelope comprisesat least one of an attack portion and a decay portion, the synthesiserbeing configured to stretch or trim the at least one of the attackportion and decay portion when shifting the pitch deviation envelope.32. Apparatus according to claim 26, wherein the synthesiser isconfigured to define the pitch deviation envelope as a stroke table forstoring in a memory.
 33. Apparatus according to claim 32, wherein thesynthesiser is configured to define the stroke table with parametersdefining an amplitude envelope.
 34. Apparatus according to claim 26,further comprising a receiver module configured to receive the at leastone manipulation parameter as a peak pitch deviation and optionally, oneor more selected from the group consisting of: scratchable unit; scratchname; stroke direction; stroke duration; pitch deviation envelope attacktime; amplitude envelope attack time; amplitude envelope decay time;stroke initial playback position.
 35. Apparatus according to claim 32,wherein the synthesiser is configured to approximate parameters definingan amplitude envelope.
 36. Apparatus according to claim 26, furthercomprising a recording module for recording a plurality of predeterminedpitch deviation envelopes and a memory module for storing the pluralityof predetermined pitch deviation envelopes.
 37. Apparatus fortransforming an input sound signal, the apparatus comprising asynthesiser configured to manipulate, in accordance with at least onemanipulation parameter, a pitch deviation envelope selected from aplurality of predetermined pitch deviation envelopes and selected withreference to the at least one manipulation parameter to derive amanipulated pitch deviation envelope, the at least one manipulationparameter comprising musical and acoustic parameters.
 38. Apparatusaccording to claim 37, further comprising a recording module forrecording a plurality of predetermined pitch deviation envelopes and amemory module for storing the plurality of predetermined pitch deviationenvelopes.
 39. A method for transforming an input sound signal, themethod comprising: selecting, with respect to at least one manipulationparameter, a pitch deviation envelope from a plurality of predeterminedpitch deviation envelopes; manipulating, in accordance with said atleast one manipulation parameter, said pitch deviation envelope toderive a manipulated pitch deviation envelope, the at least onemanipulation parameter comprising musical and acoustic parameters; andtransforming the input sound signal from a resampling of the input soundsignal with respect to the manipulated pitch deviation envelope.
 40. Themethod of claim 39, further comprising receiving the at least onemanipulation parameter as a user-defined peak pitch deviation of anoutput sound signal.
 41. The method of claim 40, wherein the selectionof the pitch deviation envelope is effected from a comparison of thepeak pitch deviation of the output sound signal with respective peakpitch deviation values of a plurality of pre-determined pitch deviationenvelopes.
 42. The method of claim 39, wherein derivation of themanipulated pitch deviation envelope is effected by shifting the pitchdeviation envelope in accordance with the peak pitch deviation of theoutput sound signal.
 43. The method of claim 42, wherein shifting of thepitch deviation envelope is by a peak pitch difference between a peakpitch of the pitch deviation envelope and the peak pitch deviation ofthe output sound signal.
 44. The method of claim 42, wherein themanipulated pitch deviation envelope comprises at least one of an attackportion and a decay portion, and the method comprises stretching ortrimming the at least one of the attack portion and decay portion whenshifting the pitch deviation envelope.
 45. The method of claim 39,further comprising defining the pitch deviation envelope as a stroketable for storing in a memory.
 46. The method of claim 45, furthercomprising defining the stroke table with parameters defining anamplitude envelope.
 47. The method of claim 45, further comprisingapproximating parameters defining an amplitude envelope.
 48. The methodof claim 39, further comprising receiving the at least one manipulationparameter as a peak pitch deviation and optionally, one or more selectedfrom the group consisting of: scratchable unit; scratch name; strokedirection; stroke duration; pitch deviation envelope attack time;amplitude envelope attack time; amplitude envelope decay time; strokeinitial playback position.
 49. The method of claim 39, furthercomprising recording a plurality of predetermined pitch deviationenvelopes and storing the plurality of predetermined pitch deviationenvelopes.
 50. A method for transforming an input sound signal, themethod comprising manipulating, in accordance with at least onemanipulation parameter, a pitch deviation envelope selected from aplurality of predetermined pitch deviation envelopes and selected withreference to the at least one manipulation parameter to derive amanipulated pitch deviation envelope, the at least one manipulationparameter comprising musical and acoustic parameters.
 51. The method ofclaim 50, further comprising recording a plurality of predeterminedpitch deviation envelopes and storing the plurality of predeterminedpitch deviation envelopes.
 52. A method of defining a scratch sound byits acoustic characteristics, the method comprising, defining theacoustic characteristics using at least one manipulated pitch deviationenvelope, the manipulated pitch deviation envelope derived frommanipulating, in accordance with at least one manipulation parameter, apitch deviation envelope selected from a plurality of predeterminedpitch deviation envelopes and selected with reference to the at leastone manipulation parameter.
 53. A method of claim 52 further comprisingdefining the acoustic characteristics using at least one amplitudeenvelope.
 54. A method of claim 52 wherein the at least one of thedeviation envelopes define one or more musical and acoustic parametersof the scratch sound.
 55. A method of claim 52 wherein the musical andacoustic parameters of the scratch sound comprises a peak pitchdeviation and optionally, one or more selected from the group consistingof: scratchable unit; scratch name; stroke direction; stroke duration;pitch deviation envelope attack time; amplitude envelope attack time;amplitude envelope decay time; stroke initial playback position
 56. Amethod of transforming an input sound signal by applying a scratchsound, the scratch sound being as defined by claim 52, the methodcomprising: selecting, with respect to one or more musical and acousticparameters, one or more pitch deviation envelopes of the scratch soundfrom a plurality of predetermined pitch deviation envelopes;manipulating said one or more pitch deviation envelopes of the scratchsound, in accordance with said one or more musical and acousticparameters, to derive one or more manipulated pitch deviation envelopes;and transforming the input sound signal by resampling the input soundsignal with respect to the one or more manipulated pitch deviationenvelopes.
 57. The method of claim 52, further comprising recording aplurality of predetermined pitch deviation envelopes and storing theplurality of predetermined pitch deviation envelopes.